The invention pertains to a centrifugal speed governor of fuel injection pumps. Such speed governors are commercially available as variable-speed governors or idling speed governors from the Bosch company under the designation EP/RSV and EP/RSF. In these speed governors, which are produced in large-scale production, the points of support and application, which are very accurately fixed in theory, divrege from the provided positions as a result of manufacturing defects. These deviations can either be corrected by means of subsequent, and accordingly expensive, treatment of the parts in question or they must be compensated for by means of a corresponding construction of the governor parts. Such compensation is achieved, for example, in the double-armed guide lever, with its box-type construction, in that the latter is constructed so as to be torsionally resilient. However, torsional resilience has the disadvantage that the control is accordingly inaccurate as a whole and inclines toward considerable scatter or straying and that the adjustability of the governor is accordingly made substantially more difficult.
If, in addition, the governor works with an adapting or torque control device in which a "fuel adaptation" is achieved, as in these EP/RS governors, in that the articulated head impacts with its side remote of the centrifugal force adjuster against an adapting pin, which is loaded by means of an adapting or torque control spring, there is the risk that whenever the articulated head is inclined relative to the working surface of the adapting pin because of the torsion of the guide lever, a displacement of the point of application, and accordingly an undesired change of the provided "adaptation", occurs.
In addition, there are adjustment errors due to friction losses of the governor which occur, for example, during the transmission of the centrifugal weight adjusting forces to the guide lever and, from the latter, to the feed quantity adjusting member. These friction losses increase naturally when distortions occur in the control linkage because of torsional resilience or other twisting. Friction losses and twisting occur particularly with adjustment errors, that is, when the transmission of force is not effected in the adjusting direction determined by means of the centrifugal force adjuster axis, so that tilting moments occur, which have a particularly disadvantageous effect at those places at which the transmission of force is effected via form-locking surfaces rather than points or lines. Deviations from the adjusting direction can result, for example, in an off-center application of centrifugal forces of the centrifugal force adjuster, wherein, in certain speed ranges, these loads, which act on one side, can lead to a hooking of the parts which are displaceable relative to one another. These undesired transverse forces also impede the governor quality because the actual force transmission lines diverge from the aligned lines which were originally provided.
With respect to the control curve, on which every governor is based, the result of the afore described deficiencies on the one hand is that this control curve has a relatively considerable scatter and, moreover, there is a smooth transition rather than a steep drop during the transition to the regulation point. But in order to define an exact control curve it is necessary that dwell points be given for the adjustment, for example, during the transition to the regulation point. These disadvantages make themselves felt particularly in the idling speed governor, in which the regulation point for preventing damage to the engine, in particular, is allowed to begin only after a given speed, which is not adjustable because of the absence of a dwell point. It is only possible to fully exploit this maximum speed of the engine when the maximum rate of rotation of the engine can be very precisely controlled by means of the fuel injection pumps.
In another known centrifugal speed governor of the type mentioned in the beginning (DE-PS No. 1011223), the adjusting piece, which is constructed as an adjusting sleeve, is guided on a shaft stub of the centrifugal weight adjuster and, by means of a roller bearing in which the articulated head is inserted with a corresponding pin, acts axially on the latter. The articulated head comprises an axle stub which extends transversely relative to the adjusting direction and on which the brackets of the guide lever act via elongated holes which are open at the bottom. This construction has the disadvantage that constructional inaccuracies of the lever bearing, as well as alignment errors of the regulating movements, are either not compensated for or are compensated for by means of the torsional elasticity of the guide lever, both of which lead either to excessive friction or to the aforementioned control errors.